Chapter 7
Elements of Microbial Nutrition, Ecology, and Growth
I.
Introduction
An abandoned open-pit copper mine in Montana is the site of a severe environmental
problem. Microbial growth in a lake at this site has resulted in an aquatic system with
very low pH and high metal content. Despite these adverse conditions, a number of
microbes thrive in the lake. Some of these microorganisms are eukaryotes that may
actually aid in the remediation of this site.
II.
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Facts of the Case
A lake at an open-pit copper mine in Montana is very acidic and severely
contaminated with dissolved metals.
Despite the low pH, many acidophilic microbes make their home in the lake.
Some of the organisms in the lake are eukaryotes (such as algae and fungi).
The metabolic activity of some members of this microbiota may actually be
detoxifying the contaminated lake.
Student questions:
1. What kind of microorganisms are members of the genus Euglena?
2. How might microbial metabolism act to detoxify the lake at this copper mine?
3. Given that freshwater has a normal pH of 6.5, what pH would the lake at
Berkeley Pit have (10,000 times more acidic)? (Rememeber! In the pH scale, a
decrease of 1 point means 10 times more acidic)
4. How could a microorganism alter the pH of its environment? Why might this be
advantageous to the microbe?”
5. Why is the water of this lake so acidic in pH?
6. Why is the lake water contaminated with high levels of metal ions?
7. How could this acidification process be useful for mining ores with low metal
content?